Generation and use of delta index

Abstract

According to an embodiment of the present disclosure, it is determined whether a delta index is beneficial based on the difference between a first version and a second version of a document, wherein the first version is associated with a first index comprising a plurality of keywords appeared in the first version. The delta index is generated for the difference between the first and second versions if the delta index is beneficial, wherein the delta index comprises a first section including information about one or more keywords affected by the difference and the information about the positions of the affected keywords.

What is claimed is: 
     
         1 . A computer-implemented method, the method comprising:
 determining a delta index based on a difference between a first version and a second version of a document, wherein the first version is associated with a first index comprising a plurality of keywords appeared in the first version; and   generating the delta index for the difference between the first and second versions if the delta index meets a generating criteria, wherein the delta index comprises a first section including information about one or more keywords affected by the difference and the information about the positions of the affected keywords.   
     
     
         2 . The method according to  claim 1 , wherein the information about positions of the affected keywords includes information about addition and/or removal of the one or more keywords. 
     
     
         3 . The method according to  claim 1 , wherein the delta index further comprises a second section including information about position changes between the first and second versions. 
     
     
         4 . The method according to  claim 1 , wherein the step of determining comprises:
 evaluating the difference between the first and second versions from at least one of the factors including:   similarity between the first and second versions,   numbers of keywords in the first and second versions,   frequencies of the keywords in the first and second versions, and   positions of the keywords in the first and second versions.   
     
     
         5 . The method according to  claim 1 , further comprising:
 searching for a keyword in the second version of the document based on the first index and the delta index.   
     
     
         6 . The method according to  claim 5 , wherein the step of searching comprises:
 querying the first index and the delta index for the keyword; and   locating the keyword in the second version based on the result of querying the first index and the delta index.   
     
     
         7 . The method according to  claim 6 , wherein the step of locating comprises:
 obtaining the keyword's position in the first version based on the first index; and   calculating the keyword's position in the second version based on at least one of the first section and the second section of the delta index, as well as the keyword's position in the first version.   
     
     
         8 . A system comprising:
 one or more processors;   a memory coupled to at least one of the processors;   a set of computer program instructions stored in the memory and executed by at least one of the processors in order to perform actions of:   determining a delta index based on a difference between a first version and a second version of a document, wherein the first version is associated with a first index comprising a plurality of keywords appeared in the first version; and   generating the delta index for the difference between the first and second versions if the delta index meets a generating criteria, wherein the delta index comprises a first section including information about one or more keywords affected by the difference and the information about the positions of the affected keywords.   
     
     
         9 . The system according to  claim 8 , wherein the information about positions of the affected keywords includes information about addition and/or removal of the one or more keywords. 
     
     
         10 . The system according to  claim 8 , wherein the delta index further comprises a second section including information about position changes between the first and second versions. 
     
     
         11 . The system according to  claim 8 , wherein the set of computer program instructions are executed by at least one of the processors in order to further perform the action of:
 searching for a keyword in the second version of the document based on the first index and the delta index.   
     
     
         12 . The system according to  claim 11 , wherein the set of computer program instructions are executed by at least one of the processors in order to perform the action of searching by:
 querying the first index and the delta index for the keyword; and   locating the keyword in the second version based on the result of querying the first index and the delta index.   
     
     
         13 . The system according to  claim 12 , wherein the set of computer program instructions are executed by at least one of the processors in order to perform the action of locating by:
 obtaining the keyword's position in the first version based on the first index; and   calculating the keyword's position in the second version based on at least one of the first section and the second section of the delta index, as well as the keyword's position in the first version.   
     
     
         14 . A computer program product, comprising a computer readable non-transitory storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:
 determining a delta index based on a difference between a first version and a second version of a document, wherein the first version is associated with a first index comprising a plurality of keywords appeared in the first version; and   generating the delta index for the difference between the first and second versions if the delta index meets a generating criteria, wherein the delta index comprises a first section including information about one or more keywords affected by the difference and the information about the positions of the affected keywords.   
     
     
         15 . The computer program product according to  claim 14 , wherein the information about positions of the affected keywords includes information about addition and/or removal of the one or more keywords. 
     
     
         16 . The computer program product according to  claim 14 , wherein the delta index further comprises a second section including information about position changes between the first and second versions. 
     
     
         17 . The computer program product according to  claim 14 , wherein the program instructions further cause the processor to:
 search for a keyword in the second version of the document based on the first index and the delta index.   
     
     
         18 . The computer program product according to  claim 17 , wherein the program instructions cause the processor to search by:
 querying the first index and the delta index for the keyword; and   locating the keyword in the second version based on the result of querying the first index and the delta index.   
     
     
         19 . The computer program product according to  claim 18 , wherein the program instructions cause the processor to locate by:
 obtaining the keyword's position in the first version based on the first index; and   calculating the keyword's position in the second version based on at least one of the first section and the second section of the delta index, as well as the keyword's position in the first version.